It has long been desired to defat nuts, thereby lowering their caloric content. However, it has often been difficult to remove significant amounts of fat from nuts without simultaneously diminishing their flavor. The present invention avoids this problem with a process of defatting nuts where the nuts retain a greater portion of their natural flavor.
The term "nuts" as used in this description includes whole nuts and pieces of nuts such as peanuts, almonds, Brazil nuts, filberts, pecans, walnuts, and the like. For conciseness, the following disclosure will center around the production of low-fat peanuts. It is not, however, limited to peanuts, because the principles of the present invention, as it relates to peanuts, are also applicable to other nuts.
The basic procedures for preparing partially-defatted nuts by pressing oil from them have been known for a number of years. U.S. Pat. Nos. 2,003,415 to Ammann and 3,294,549 to Vix et al. disclose examples of such processes. Broadly, these methods involve pressing nuts until the desired quantity of oil is removed and then steaming or cooking the partially-defatted nuts in water until the nuts are reconstituted to substantially their original size and shape. The nuts have a substantially high moisture content. Further work on the process of Vix et al. is described in a series of articles entitled "Development and Potential of Partially Defatted Peanuts," Peanut Journal and Nut World, January and February 1967, and an article entitled "Low Calorie Peanuts," Food Processing/Marketing, September 1965.
Later workers, encouraged by the appeal of low fat products to weight conscious consumers, continued work in this area.
U.S. Pat. No. 3,740,236 to Baxley indicates that roasted peanut flavor appears to be reduced in proportion to the percentage of the peanut oil removed during the pressing process. Baxley, however, does not attempt to prevent this flavor loss but, instead, provides a process for improving the flavor of the nuts after defatting. In this process, the defatted nuts are reconstituted in an aqueous binder solution which may contain flavors.
U.S. Pat. No. 3,645,752 to Baxley discloses a process of improving the flavor of partially-defatted nuts by quenching them in a flavored oil after roasting.
U.S. Pat. No. 4,049,833 to Gannis et al. also recognizes the adverse effect defatting has on the flavor and texture of partially-defatted nuts and suggests reconstituting the partially-defatted nuts with a glycerol-containing solution prior to roasting. When roasted, the reconstituted nuts are disclosed to have an improved flavor, texture, and storage stability.
U.S. Pat. No. 4,329,375 to Holloway, Jr. et al. discloses a process for producing low fat nuts which retain more of their natural flavor and aroma. This involves preroasting the nuts, pressing them to partially remove the oil, and then completing roasting. An improvement on this process is disclosed by U.S. Pat. No. 4,466,987 to Wilkins et al.
The exact reason for the flavor loss in partially-defatted nuts is not fully understood. The Doctoral Dissertation of M. E. Mason, entitled "Procedures in Studying and Factors Influencing the Quality and Flavor of Roasted Peanuts," (Oklahoma State University, 1963, pp. 63 and 64), indicates that oil pressed from peanuts contains aleurone grains, among other particulates, which appear to contain flavor precursors. The Mason dissertation, however, was not concerned with the preparation of low-fat nuts, but simply with gaining a better knowledge of the source and identification of flavor principles in peanuts.